In recent years, not only in the field of pharmaceuticals, but also in fields such as health foods and nutritional foods, the development and marketing of products in the form of tablets has become increasingly common. Against this background, orally disintegrating tablets which can be taken without water are attracting much attention. Orally disintegrating tablets must have oral disintegratability that allows rapid disintegration inside the mouth, but must also have sufficient tablet strength (hereafter referred to as “hardness”) that no problems arise from the production steps through to the packaging steps, shipping, and subsequently handling. This oral disintegratability and this hardness are usually mutually opposing properties, and therefore the tableting of orally disintegrating tablets has typically required the addition of various additives and the use of special production devices. Further, the tableting costs for orally disintegrating tablets are borne by the consumers and patients, and by the finances of the country. Accordingly, the development of technology which enables the tableting of orally disintegrating tablets to be performed easily using inexpensive raw materials has been keenly sought.
In response to such demands, Patent Document 1 proposes an orally disintegrating tablet of the composition described below (see Claim 1).
“An orally disintegrating tablet containing a processed starch having a degree of gelatinization of 30 to 60% dispersed throughout the tablet, and also containing a medication and a saccharide.”
During tableting of the orally disintegrating tablet of the composition described above, in order to ensure favorable oral disintegratability, lactose and/or D-mannitol must be added to lower the moldability (see claims 8, 10 and 14, and paragraph 0021 of the same document). At the same time, a water-soluble polymer such as a crystalline cellulose (for example, hydroxypropyl cellulose) must be added to the mixture to impart satisfactory hardness (see claim 11 and paragraph 0024 of the same document).
The orally disintegrating tablet disclosed in this Patent Document 1 uses comparatively inexpensive starch. However, as described above, auxiliary excipients such as a saccharide and a crystalline cellulose must be added separately from the starch. As a result, it cannot necessarily be claimed that the raw material costs are inexpensive and the tableting costs are also inexpensive.
On the other hand, Patent Document 2 discloses a method for producing starch particles having the composition described below.
“A method for producing starch particles, the method including coating the surface of a fluid β-type starch with an α-type starch by spraying a starch paste onto the β-type starch and then performing heating and drying, thereby generating a proportion of the α-type starch on the surface of the β-type starch equivalent to 5 to 20% of the total.”
However, these starch particles are not produced with the intention of achieving oral disintegratability for tablets, and in a similar manner to Patent Document 1, require the addition of a saccharide such as lactose or a syrup or the like as an auxiliary excipient (see Patent Document 2, Reference Examples 1 to 4), meaning they suffer from the same problems as described above.